The racemic mixture of certain compounds of the present invention is described in U.S. Patent 4,954,515 and 5,098,921. In particular, Example 2 of both patents describes the racemic mixture of the compound of Formula I set forth below wherein X is bromo. The racemic mixture of certain compounds of the present invention is also described generically as starting materials or intermediates in the following U.S. Pat. Nos. 4,596,817; 4,631,289; 4,757,148. Additionally, the racemic mixture of certain compounds of Formula I is described generically in U.S. Pat. No. 4,241,060 as hypoxic-cell radiosensitizers.